Figure 2.

Effect of astragaloside IV (AS-IV) on nitric oxide production in endothelial cells: (A) human umbilical vein endothelial cells (HUVECs) were incubated with various concentrations of AS-IV (3, 10, or 30 µmol/L) for 6 h, (B) HUVECs were incubated with AS-IV (30 µmol/L) for 0–12 h, and (C) HUVECs were preincubated with or without N^G-monomethyl-L-arginine (L-NMMA, 1 mmol/L), LY294002 (10 µmol/L), or ethylene glycol tetraacetic acid (EGTA, 500 nmol/L) for 1 h and then incubated with AS-IV (30 µmol/L) for an additional 6 h. The levels of nitrite in the culture supernatant were measured by the use of Griess assay. ⁣^∗p < 0.05 and ⁣^∗∗p < 0.01 compared with the control group; †p < 0.05 compared with HUVECs exposed to AS-IV alone.